Electronically controlled high pressure fuel systems are known and commonly used in the automotive and heavy duty truck industries. Such systems may include a fuel pump operable to provide high pressure fuel to a collection unit that supplies the pressurized fuel to one or more fuel injectors. One or more pressure sensors are typically provided for monitoring and controlling the fuel pressure throughout the system.
An example of one such system is described in U.S. Pat. No. 5,678,521 to Thompson et al., which is assigned to the assignee of the present invention. The Thompson et al. fuel system includes a pair of cam driven high pressure fuel pumps operable to pump fuel from a low pressure fuel source to an accumulator. The accumulator passes the high pressure fuel to a single injection control valve which is electronically controllable to supply the fuel to a distributor unit. The distributor, in turn, distributes the fuel to any of a number of fuel injectors. The accumulator includes a pressure sensor for monitoring accumulator pressure. An electronic control unit monitors accumulator pressure, throttle position and engine speed, and is operable to control the operation of the fuel system in accordance therewith.
High pressure fuel systems of the type just described, while having many advantages over prior mechanical systems, have certain drawbacks associated therewith. For example, failure of electrical and/or mechanical components of the system may result in total system failure, in which case the engine is often shut down leaving the vehicle and occupant stranded. In severe cases, failure of such components can lead to catastrophic destruction of fuel system components.
What is therefore needed is a system for diagnosing faults and failures in an electronically controlled fuel system of the type just described. Such a system should ideally log fault codes indicative of fuel system related failures, and pressure sensor failures in particular, to assist in repair efforts, and should additionally provide for a limp home fueling operational mode so that the vehicle can be driven out of danger and/or to a repair facility.